1. Field of the Invention
The invention relates in general to methods and devices for mounting an electrical contact to an insulated multi-strand or single strand wire and, more particularly, embodiments of the present invention relate to improvements in methods and devices for mounting contacts onto insulated multi-strand and single strand wires by indenting the contact into the multi-strand or solid wire to form an electrical contact, and crimping the contact around the insulation to form an hermetic seal between the insulation and the contact in one crimping cycle.
2. Description of the Prior Art
Multi-strand and single strand aluminum alloy wires have been widely used for various electrical wiring purposes, and recently in aircraft and aerospace applications where a reduction in the weight of the wiring is achieved by such use. Solid or multi-strand aluminum wires typically include a core of aluminum alloy metal strand(s) surrounded by a coating of flexible electrical insulation material. Aluminum and its alloys, for example, are typically susceptible to corrosion if the coating of insulation is broken. The insulation is always broken when the wires are cut to allow joinder to various fittings and contacts. The multi-strand and solid wire core projects beyond the cut insulation to permit direct electrically conductive connection with the contact. Such contacts typically are in the form of a pin that is adapted to plug into a socket to complete a desired circuit. It has been recognized that the connections between wires, particularly aluminum wires, and contacts should be made in such a way that the cut end of the coating is hermetically sealed to the electrical contact. This prevents moisture from entering the cut end and causing corrosion of the metal core. To this end, electric contacts for multi-strand and solid core electrical wires are typically designed so that a dual crimping action is required to mount them. One crimping action seals the contact to the coating of insulation, and another crimping action (indenting) forms the electrical connection between the metal core and the contact. Tools to accomplish this dual crimping action, particularly hand tools, had been previously proposed. See, for example, Kelly et al. US 2004/0072378, Pub. Apr. 15, 2004. Dual crimping of multi-strand electrical wires where hermetic sealing is not expected had been proposed. See, for example, Klemmer et al. U.S. Pat. No. 5,415,015, and Ohsumi et al. U.S. Pat. No. 6,782,608. Previous expedients were generally less than completely satisfactory because the crimp formed seals between the coating and the contact often failed. Also, the previous crimping equipment was generally time consuming to work with because it was difficult and time consuming to change crimping dies to accommodate different gauges of wire, crimper tool malfunctions, or the like. Such previous equipment was generally incapable of accommodating a full range of wire gauges with one tool. “Single wire gauge” crimp tools of various designs had been proposed. See, for example, Fischer U.S. Pat. No. 3,713,322 (four radially opposed dies actuated by a rotatable cam for crimping a contact to a multi-strand wire).
Those concerned with these problems recognize the need for an improved dual crimping tool.